scientific nameVanessa cardui (Linnaeus)common name Painted LadyhabitatA migrant that can be found in almost any habitat in years that it is common.seasonalityCan be found throughout the season, from late April into October.identificationThere are two other similar Vanessa; the first, V. virginiensis, occurs only very rarely as a migrant in Alberta, and the Painted Lady can immediately be distinguished from virginiensis by the row of three to four smaller eyespots on the hindwing underside; virginiensis has only two, much larger spots. Compared to the West Coast Lady (V. annabella), cardui has a large white spot two-thirds up the leading edge of the forewing, which is orange in annabella; cardui is also larger.Royal Alberta Museum page
There are no named subspecies.life historyThe light green cylindrical eggs have vertical ribs. Mature larvae are grey-brown with fine yellow and black markings and yellow branched spines (Guppy & Shepard 2001). Larvae live in silken leaf-nests on the hostplant (Layberry et al. 1998).
This species is rare or absent in Alberta in most years, but in years that populations build up in the southern United States, worn and often tattered migrants appear in May to lay their eggs, having flown thousands of miles. The offspring of these migrants emerge from July onwards. Since it is rare or absent in most years in Alberta, it is thought that Painted Ladies cannot overwinter here, and re-colonize in good migrant years. It is not known if summer brood individuals attempt a southward return migration in the fall here; they may in the southwestern US (Scott 1986), but there is no evidence they do so in British Columbia (Guppy & Shepard 2001).
conservationNot of concern.diet infoMany composites (Asteraceae) have been recorded as larval hosts, but thistles (Cirsium spp.) seem to be favoured in western Canada (Guppy & Shepard 2001).rangeThis butterfly is more widespread tha nany other species in the world; although it does not tolerate hard winter forsts, migrants have been found on every continent save Antarctica; recorded as far north as northern Greenland (Scott 1986).taxonomic hierarchy

(a) The Painted Lady, Vanessa (Cynthia) cardui is periodic, mass invader of Alberta. When weather conditions are favourable (lots of rain in the US deserts), the expanding populations in the US are aided by northerly winds to reach new breeding areas. Butterflies from south of the border arrive in Alberta in late April & early May. Readily finding the suitable larval food plants, (Carduus spp., Cirsium ssp. Centaurea, Actinium spp.). Many other larval food plants are known, e.g. I found them in Edmonton on sunflower (Helianthus sp.). Females lay eggs, which hatch & produce 2-3 local generations of new butterflies. The locally produced generation continues to breed & expand the range, moving farther north. In 1975 I collected several specimens in Norman Wells, NWT. The erratic periodicity of invasions to Alberta greatly varies, perhaps the largest occurred in 2005. It appears that, recently, the periodicity of mass invasions increased (1992, 2003, 2005, 2008, 2009, 2011). The Painted Lady does not hibernate like the Anglewings, & the locally produced offsprings are not able to survive the first hard frost. A southward return migration from Alberta in the fall of 1983 was reported by Myers, M. T. in 1985 (Canad. Field Naturalist, 99: 147-155.)
(b) On taxonomic grounds, the species of the cardui group (e.g. cardui, carye, annabella, virginiensis) have been treated by some taxonomist as members of the genus Cynthia Fabricius, 1807. The atalanta group (e.g. atalanta, indica, vulcania) as members of the genus Vanessa Fabricius, 1807. It should be noted that Vanessa atalanta does survive the winter in Alberta in hibernation, whereas Cynthia cardui does not. The egg of Cynthia cardui has 16 longitudinal keels, whereas the egg of Vanessa atalanta has 10 keels. In both species the eggs are laid singly, on the upper surface of leaves of the larval food plant.
The larvae in both species are solitary.

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